Many highly differentiated in vitro epidermal and dermal/epidermal sin models have been developed which are useful for: 1) transdermal drug delivery systems, 2) skin transplantation, and 3) dermal irritancy testing. For the most part, these models incorporate epidermal keratinocytes and/or dermal fibroblasts but do not include melanocytes, the pigment cells of the integument which provide protection from potentially harmful ultraviolet (UV) solar irradiation. In addition, melanocytes are believed to participate in the inflammatory response of skin and are obviously required to allow the study of skin pigmentation disorders, UV induced skin damage, etc. Utilizing a serum free, highly differentiated keratinocyte based epidermal model previously developed as a starting point, this research will attempt to develop a similar serum free culture system which allows the incorporation of melanocytes. A serum free medium will be developed using additives known to stimulate the proliferation and maintenance of melanocytes in monolayer culture. Three dimensional, highly differentiated epidermal constructs will be cultured and characterized using light and electron microscopy, a melanocyte biochemical marker, and melanin synthesis. Finally, an initial investigation of the model's response to stimuli known to affect melanocytes in vivo such s UV will be made. These studies will lay the groundwork for Phase II research which will include an in-depth analysis of the effect of UV on the epidermis, photoaging of skin, and other melanocyte related skin phenomena.